65.併用digoxin與erythromycin產生藥品交互作用時，最主要的原因為何？
(A)改變腸胃道的pH值
(B)增加藥品的代謝
(C)競爭藥品受體的結合點
(D)改變腸胃道內細菌的含量

補充 warfarin（特別）

大部分廣效型抗生素會殺死製造Vit.K前驅物的細菌而增加warfarin抗凝作用

但有2個例外，Dicloxacillin 和 Nafcillin，會減少抗凝作用

          Dicloxacillin  Nafcillin    --Wafarin  

口訣     DNA    （降低）

65.Erythromycin與下列藥品均有交互作用，何者之機轉與其他三者不相同？ 
(A)carbamazepine 
(B)cyclosporine 
(C)digoxin 
(D)tacrolimus

專技 - 調劑學與臨床藥學- 103 年 - 103-1-藥師-調劑學與臨床藥學#14227
答案：C 

兩個機轉：
1. macrolide 抑制p-gp，使digoxin 無法排除而累積

2. macrolide 清除可以代謝digoxin 的細菌，使更多的digoxin 被吸收

Macrolide inhibition of P-glycoprotein (P-gp) mediated transport of cardiac glycosides could theoretically lead to increases in glycoside bioavailability and/or decreases in renal clearance. Several macrolides inhibit P-glycoprotein (P-gp) mediated transport of digoxin and digitoxin to some extent in vitro with telithromycin showing the greatest inhibitory potency, followed by clarithromycin, followed by azithromycin and erythromycin.

A second theory, which has not been the subject of future study with macrolides since its original proposal, is that antibiotics including erythromycin could eradicate gut bacteria capable of metabolizing digoxin, such as Eubacterium lentum, thus leaving greater quantities of unmetabolized drug available for absorption.

UpToDate Lexicomp Cardiac Glycosides / Macrolide Antibiotics